Research

Dr. Narayanan’s laboratory focuses on two topics:

Pathology of bacterial adherence and injury to host cells.

We are also studying the molecular structure and expression of virulence determinants in Fusobacterium necrophorum. Leukotoxin is one of the major virulence factors of F. necrophorum and plays a critical role in causing multifocal coagulative necrosis of the liver in bovines. The leukotoxin is a large secreted exotoxin (approximately 336 KDa) which causes apoptosis of target cells at lower concentrations and necrosis at higher concentrations. Efforts are also on to elucidate the role of the outer membrane proteins in the adherence of F. necrophorum subspecies to host cells and its effect on animal and human diseases. In-vivo, in-situ and in-vitro studies are focused to understand the virulence of this organism.

Molecular biology of antimicrobial resistance among bacteria.

Antimicrobial resistance is of growing global concern in human and veterinary medicine. Understanding the role of various environmental (ecological) and intrinsic factors that lead to prevalence, amplification and spread of antibiotic resistance is vital. In our lab, we primarily utilize the feedlot industry as a model to understand the role of animal industry in amplification and spread of antimicrobial resistance and virulence genes among food-borne pathogens such as E. coli, Salmonella andEnterococcus. We are interested in identifying non-traditional selection pressures (factors other than exposure to antibiotics) that contribute to multi-drug resistance among intestinal commensals and food-borne pathogens. We have identified acute stress related host catecholamines as an enhancer of conjugative plasmid transfer.

I coordinate Systemic Pathology Course in which I teach 30 lectures and approximately 35 labs. I primarily focus on the pathologies of cardiovascular, nervous, urinary, reproductive, musculoskeletal and integumentary systems.

I teach 4-6 lectures and approximately 8 to 10 labs in General Pathology course including the pathology of the hemolymphatic system.

Pathogenic Mechanisms is a higher level graduate course designed to understand the mechanisms by which bacteria alter the host systems to their advantage and cause disease. The first half of the course will focus on learning host environment in health and disease and the second half will address bacterial pathogenesis in animal, human and zoonotic diseases.

Diagnostic Pathology

I perform necropsies and biopsies during summer and fall semesters and enjoy working with students on senior Diagnostic Medicine rotation (DMP785).

Selected peer-reviewed publications

(ªIndicates graduate or undergraduate student and *Indicates the corresponding/senior author)